Without quite knowing why, Acrocanthosaurus lived to the public under the shadow of T.Rex, still a great unknown to most and undervalued its role as a hunter at the time of the Cretaceous in North America and Europe.

About the size of T.Rex, the Acrocanthosaurus was a cousin of Allosaurus and, as this was a hunter specializing in large animals, giant sauropods like Diplodocus weighing 6 or 7 times or Pleurocoelus.
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The name of this lizard Acrocanthosaurus means "thorn lizard high" and indeed, when it was discovered, even mistook him for the BIG SPINOSARUS (King of Kings). The theme of the spines always generates controversy and do not become experts agree: if they were to regulate the temperature, if it was to swim, to show your mood, or to house unions with strong muscles ... too numerous to write about this but we'll see another day.

Speaking of muscles, the Acrocanthosaurus was very muscular and strong, much more than others allosaurids. Something like an Allosaurus largest and steroids. It measured 12 meters and weighed 5.6 tons, and this made ​​him a bit slow *. He ran and ran up to the big sauropods (which is not that they were cheetahs) long necks and hooked to these formidable pulling their strong claws and bite with all his weight down, dropping these titanic beasts.

* It was the weight and slow what they did to specialize in hunting large animals, or vice versa, hunting big beasts Acrocanthosaurus led to larger and more robust. Finally, the case is to specialize in this way produced an end. Forms were disappearing with the big sauropods, the Acrocanthosaurus were increasingly less likely to hunt and smaller dams could more easily escape them. His strength was his undoing.

When I wrote the post of Allosaurus Europeaus, also promised to write about the Allosaurus fragilis, the best-known species whose fossilized bones have more information to the expert paleontologists.

But not only important for the amount of fossil fuels. Anyone who has heard or knows anything about the dinosaur Allosaurus know that this was a T. Rex of his time. It was a prehistoric monster that was in the top of the food chain, a predator with a bite capable of prey animals as large as Stegosaurus and Diplodocus.

Fortunately for the Allosaurus did not have to deal with T.rex (who lived 80 million years later), the Spinosaurus (30 million years later) or Giganotosaurus (60 million years ago). Possibly the only species of dinosaur that could stand up was Saurophaganax that like Allosaurus lived for about 150 million years in the late Jurassic.

Their physical characteristics are:

Length: Nearly 30 feets long.Height: 13 feets.Weight: 6000 lb.

(T.rex- 43 for long., 18 tall and nearly 13.000 lb)

Although smaller than T. rex, Allosaurus's body was much the same way, the only notable difference was that his front arms were compared with the body, stronger and longer.

Another feature is that the Allosaurus (some experts believe) reached high speeds ... of course for these sizes of dinosaurs. Reached speeds of up to 6,2 mill / h and this speed could reach any of stalking and its victims.

Once the victim came to them with a bite attack stubborn 70-curved teeth inward dams prevented their escape, lest they (the prisoners) do without the piece of meat that was trapped in its jaws Allosaurus.

The Ceratosaurus had skulls with a structure similar to the dorsal horn on the snout, centrally placed in the nasal cast. They had fused sacral bones (Synsacrum) and the pelvic bones together and held together this structure. A row of small bony nodules or osteoderms were presented under the middle of the back.

The Ceratosaurus could have competed with Allosaurus and Torvosaurus for the same prey (giant sauropods Diplodocus, Apatosaurus and Camarasaurus), but this was smaller by about 6 to 8 meters in length, 2.5 in height, and weighing from 500 kg to 1 tonne would have an ecological niche occupied separately from their larger cousins. Moreover, the Ceratosaurus had a longer body and supple, with a tail shaped like a crocodile. This suggests that was a better swimmer and Torvosaurus Allosaurus. A recent study showed that Robert Bakker Ceratosaurus dams usually hunted waterfowl, such as fish and reptiles, but also had great potential to feed on dinosaurs. The study also indicates that adults and juveniles sometimes ate together. This evidence is, of course, very debatable and Ceratosaurus teeth marks are very common in large dams fossils of dinosaurs on land. Another common theory is that the Ceratosaurus has preyed primarily on Dryosaurus, Camptosaurus, and other ornithopods, since it seems a Lonely Hunter adults unable to break down sauropods. An alternative is that the ceratosaur eat carrion of large bodies of sauropods, displacing small small predators.

Allosaurus was a large bipedal predator with a large skull, equipped with dozens of large, sharp teeth. It averaged 8.5 meters (28 ft) in length, though fragmentary remains suggest it could have reached over 12 meters (39 ft). Relative to the large and powerful hindlimbs, its three-fingered forelimbs were small, and the body was balanced by a long, heavy tail.

Allosaurus fragilis, the best-known species, had an average length of 8.5 meters (28 ft), with the largest definitive Allosaurus specimen estimated at 9.7 meters long (32 ft), and an estimated weight of 2.3 metric tons (2.5 short tons).

The skull and teeth of Allosaurus were modestly proportioned for a theropod of its size.

Allosaurus is a genus of large theropod dinosaur that lived 155 to 145 million years ago, in the late Jurassic period in the Kimmeridgian and Tithonian, in what is now North America and Europe.

Allosaurus fragilis had an average length of 8.5 meters (28 ft), with the largest definitive Allosaurus specimen (AMNH 680) estimated at 9.7 meters long (32 ft), and an estimated weight of 2.3 metric tons (2.5 short tons).Allosaurus was a typical large theropod, having a massive skull on a short neck, a long tail and reduced forelimbs. As with dinosaurs in general, weight estimates are debatable, and since 1980 have ranged between 1500 kilograms (3300 lb), 1000 to 4000 kilograms (2200 to 8800 lb), and 1010 kilograms (2230 lb) for modal adult weight (not maximum).

Several gigantic specimens have been attributed to Allosaurus, but may in fact belong to other genera. The closely related genus Saurophaganax (OMNH 1708) reached perhaps 10.9 meters (36 ft) in length, and its single species has sometimes been included in the genus Allosaurus as Allosaurus maximus, though recent studies support it as a separate genus. Another potential specimen of Allosaurus, once assigned to the genus Epanterias (AMNH 5767), may have measured 12.1 meters in length (40 ft). A more recent discovery is a partial skeleton from the Peterson Quarry in Morrison rocks of New Mexico; this large allosaurid may be another individual of Saurophaganx.

Skull

Skull of the Allosaurus fragilis skeleton mounted in the lobby of the San Diego Natural History Museum. The skull and teeth of Allosaurus were modestly proportioned for a theropod of its size. Paleontologist Gregory S. Paul gives a length of 845 millimeters (33.3 in) for a skull belonging to an individual he estimates at 7.9 meters long (26 ft). Each premaxilla (the bones that formed the tip of the snout), held five teeth with D-shaped cross-sections, and each maxilla (the main tooth-bearing bones in the upper jaw) had between fourteen and seventeen teeth; the number of teeth does not exactly correspond to the size of the bone. Each dentary (the tooth-bearing bone of the lower jaw) had between fourteen and seventeen teeth, with an average count of sixteen.

The skull had a pair of horns above and in front of the eyes. These horns were composed of extensions of the lacrimal bones,and varied in shape and size. There were also lower paired ridges running along the top edges of the nasal bones that led into the horns. The horns were probably covered in a keratin sheath and may have had a variety of functions, including acting as sunshades for the eye, being used for display, and being used in combat against other members of the same species (although they were fragile). There was a ridge along the back of the skull roof for muscle attachment, as is also seen in tyrannosaurids.

Allosaurus is a genus of large theropod dinosaur that lived 155 to 145 million years ago, in the late Jurassic period (Kimmeridgian to Tithonian). The name Allosaurus means "different lizard" and is derived from the Greek αλλος/allos ("different, strange") and σαυρος/sauros ("lizard"). The first remains that can definitely be ascribed to this genus were described in 1877 by Othniel Charles Marsh. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles, and has been a lead dinosaur in several films and documentaries.

Allosaurus was a large bipedal predator with a large skull, equipped with dozens of large, sharp teeth. The preys of the Allosaurus were the Diplodocus or Stegosaurus.